7 – Feature Logic with Weak Subsumption Constraints

Publisher Summary This chapter discusses feature logic with weak subsumption constraints. The extension discussed in the chapter is a weak subsumption constraints, is a mechanism of one-way information flow, often proposed for a logical treatment of coordination in a feature-based unification grammar. It can be informally described as a device which enables one to require that one part of a (solution) feature structure has to be subsumed by (be an instance of) another part. This extension to the basic feature logic of variables, features, atoms, and equational constraints, provides a means for one-way information passing. Therefore, from practical point of view direct clashes, that is, clashes which are not mediated through subsumption constraints, observed during the derivation of the algorithm should be handled as early as possible. To detect clashes that are mediated through subsumption constraints, more complex operations will be necessary.